问：
In supervision and random inspection, which items are plastic packaging most likely to fail?
答：
- Size deviation (cutting corners): If the actual thickness or length of the shopping bag is less than the nominal value, or if the width deviation is too large. This is the most common defect, mainly due to unreasonable production process or cost-saving measures.
- Falling dart impact: Simulates the packaging bag's impact resistance. Failure usually occurs due to improper raw material formulation (such as adding too much calcium carbonate) or insufficient thickness, making it prone to breaking when filled with contents.
- Sealing strength (bottom leakage): The bottom seal of the bag is not secure. When heavy objects or liquids are placed inside, the bottom cracks. This is usually due to improper sealing temperature, pressure, or process control.
- Component analysis (fake degradation): For plastic products that claim to be "degradable", it was detected that they contain ordinary polyethylene (non-degradable components), which is an act of deception by the manufacturers.
问：
What physical properties need to be tested for plastic packaging?
答：
- Barrier performance: Oxygen permeability and water vapor permeability. These are crucial for food and medicine. The lower the values, the better the preservation and moisture-proofing effect.
- Tensile strength and elongation at break: Tests whether the packaging bag is prone to being pulled apart, reflecting the toughness and strength of the material.
- Heat sealingstrength: Measures the maximum pulling force that the sealed part of the bag can withstand to prevent the contents from leaking.
- Impact resistance: The ability of the packaging to withstand being punctured by sharp objects (such as bones, sharp edges of parts).
- Sealing performance: Through vacuum or pressure tests, check whether there are any pores or leakage points in the overall packaging.
问：
Why does plastic packaging have an unpleasant smell? How can it be determined during the inspection process?
答：
- Solvent residue: During the printing or laminating process, if inferior ink or adhesives containing benzene and ketones are used and the drying is not thorough, the residual solvents will seep in and cause a pungent odor.
- Additive degradation: During the plastic's high-temperature plasticization process, additives such as antioxidants and lubricants decompose and produce odors.
- Recycled material usage: The use of unclean recycled plastics has introduced the odor of the original packaging contents.
Testing methods typically involve using gas chromatography to determine the total amount of solvent residues and the content of benzene series substances. At the same time, sensory tests (olfaction) are also required for judgment.
问：
What are the reasons for the "failure of the sealing test" in the plastic packaging inspection?
答：
- Incorrect sealing parameters: If the sealing temperature is too low, it will result in incomplete sealing; if the temperature is too high, the sealing area will be melted and wrinkled.
- Sealing surface contamination: There is oil, powder or water stains on the sealing area, which prevents complete fusion.
- Material issue: The film contains impurities or crystal points, resulting in incomplete fusion at the sealing area.
- Instrumentissue: The surface of the heat sealing knife is uneven or the pressure is not uniform.
问：
What are the differences in testing requirements between biodegradable plastics and ordinary plastics?
答：
In addition to the conventional appearance and physical properties, biodegradable plastics must demonstrate their "degradation" characteristics:
Items to be inspected:
Component analysis: Confirm whether there are non-degradable components such as polyethylene (this is the area prone to failing the inspection).
Biodegradation rate: Under composting conditions, the proportion of materials converting into carbon dioxide should typically reach over 90%.
Relative biodegradation rate.
Physical performance considerations: Biodegradable plastics are generally more "precious" than ordinary plastics. Their drop-weight impact and leak resistance properties are more likely to fail due to moisture absorption during storage or poor production processes.
